Anti-Inflammatory Effect of an Apigenin-Maillard Reaction Product in Macrophages and Macrophage-Endothelial Cocultures

Chronic inflammation is involved in the progression of various diseases, while dietary flavonoids are reported to possess antioxidative and anti-inflammatory properties against age-related diseases. Previously, an apigenin-Maillard reaction product, dimethylglyoxal apigenin (DMA), was identified by us and demonstrated to be antioxidative. In this study, we investigated the inhibitory effect of DMA on advanced glycation end product- (AGE-) induced inflammation in macrophages and macrophage-endothelial cocultures. Results showed that DMA remarkably inhibited the mRNA and protein expression of receptor for AGEs (RAGE), thereby inhibiting the production of ROS and proinflammatory cytokines, including tumor necrosis factor- (TNF-) α, interleukin (IL) 1, IL 6, and monocyte chemoattractant protein- (MCP-) 1 in RAW 264.7 cells. In the coculture system which was performed in the Boyden chamber, macrophage infiltration and adhesion to endothelial cells were significantly suppressed by DMA. Further study indicated that DMA decreased AGE-evoked IL 6 and MCP-1 secretion, which might be achieved through RAGE and its downstream-regulated transforming growth factor- (TGF-) β1 and intercellular adhesion molecule (ICAM) 1 expression in the coculture system. In conclusion, our study demonstrates that DMA, a thermally induced compound, has anti-inflammatory activity in both macrophages and macrophage-endothelial cocultures, offering a promising approach for slowing down the development of chronic diseases.

Effect of Dry Heat Temperature and Moist Heat Pressure on Canola Meal for Ruminant Utilisation. Part II: Maillard Reaction Product Formation and Structural Characteristics

The effects of a range of barrel dry heat temperatures (20 to 180 oC), and moist heat pressure (MHP) (120 oC 15 min 192 kPa) on Maillard reaction product (MRP) formation and canola meal structural characteristics were investigated. Increasing dry heat temperature was negatively correlated with meal whiteness L* and yellowness b* (early-MRP) and positively with surface hydrophobicity. Relative to control meal, MHP increased early-MRP, redness, browning index (late-MRP), and acidity; and decreased L*, surface hydrophobicity, b*, and Abs294nm (intermediate-MRP). Dry heat-associated changes in surface hydrophobicity suggest protein unfolding and side-chain modifications. Lack of high MW polypeptides at dry heat temperatures of 160 and 180 oC imply protein denaturation and formation of insoluble polypeptides. Specific dry heat temperatures increased surface lipid and induced the formation of protein matrix and aggregation. Meal surface morphology rounded and flattened at specific dry heat temperatures, and smoothed with MHP. Differences in lipid-related functional groups were evident between dry heat temperatures, and with MHP. Treatment with MHP affected amide I and II, α-helix, β-sheet, their respective ratios and the total protein fingerprint region; fragmented meal into proteolysis-resistant protein aggregates with crevices containing lipid droplets; and, reduced solubility of canola meal polypeptides > 40 kDa. The changes observed may have a great effect on ruminal degradation and supply of protein and AA for ruminant utilisation.